Temperatures for the 108th Boston Marathon are expected to reach the mid-80s, according to the National Weather Service. The average maximum for April 19 is 57.

The good news, if there is any, is that there will be some cloud cover and the expected 20 to 30 mph sustained winds will be at the backs of the runners.

Rosenberger has been through this before, and it's not fun.

"Every marathon I have run the temperature has been horrible," the Eau Claire, Wis., resident said on Sunday, the day before his first Boston Marathon, seventh overall. "I ran a marathon in Milwaukee in October a few years ago, when it was in the 80s."

The high temperatures will probably prevent the elite runners from setting any records, and the rank-and-file can probably forget about establishing personal bests, said Dr. Jim Barahal, who has been the president of the Honolulu Marathon since 1987. It gets so hot and humid in Hawaii in early December that the race starts at 5 a.m.

"The heat is never an advantage in terms of performance," said Barahal, even for those elite runners used to training in extremely hot weather. "It will slow times."

Some of those who may be most affected by the heat are the 46 Alaska residents entered in the race. The group from Alaska, where temperatures are still in the 30s and 40s and some rivers are still frozen - includes five runners from Southeast - Zane Clark of Juneau, Kyle Hebert of Douglas, Deborah Rudis of Juneau, Michael Schwarte of Wrangell and Michael Spence of Ketchikan.

Everyone's metabolism is different, and some people, no matter where they are from, deal with the heat more efficiently than others.

Even with temperatures in the 80s, Monday's race will not approach the brutal conditions Jack Fultz won under in 1976 when the temperature at the start line was 96 degrees. That year, Fultz developed his own way to stay cool.

"I laid around the shade and then soaked before the race started," said Fultz, who now coaches the Dana-Farber Marathon Challenge team, which has about 500 runners entered in Monday's race to raise money for cancer research.

The field of 20,400 official entrants is the second largest in the 108-year history of the event, second only to the 100th anniversary field of more than 38,000 in 1996.